A one-piece closet of a low silhouette type is known (for example, see Japanese Utility Model Application Laid-Open No. 106584/1986).
In a water closet of this kind, the height dimension of a flushing tank is adjusted to a closet body as much as possible so as to provide a united impression.
Therefore, sufficient water head cannot be obtained, and the feed water momentary flow rate which is a great factor in controlling the flushing function of a closet is extremely low as compared with that of a closet of the type in which the flushing tank is mounted on the closet body and a closet of the type in which a flush valve is used as a feed device.
Generally, a closet of a wall drain type has a a drain hole set to 100 to 150 mm from a floor surface in terms of execution of a closet and a function of a closet. However, when a one-piece closet of the low silhouette type employs the wall drain type to secure the aforesaid drain hole height, the head from the water surface of a bowl portion to the drain hole decreases and a satisfactory function cannot be achieved with the aforementioned poor condition being present. Therefore, no one-piece closet of the wall drain type has been present in commerce so far.
On the other hand, since a water closet of a one-piece type is considered as a luxury closet, this one-piece type closet has been desired to be installed in luxury mansions, suite rooms in luxury hotels, and the like.
However, in hotels, mansions and the like, ceiling beams often obstruct drain pipes, and in case of high buildings or the like, the ceiling height is often obtained by removal of piping space in the ceiling. Therefore, the conventional one-piece type water closet which employs the floor drain type wherein drain pipes need be installed under the floor cannot satisfy the above-described demand of the market.